1. Field of the Invention
The present invention relates to cough suppressants and to treatments for respiratory conditions, and particularly to antitussive and bronchodilator use for an enaminone ester, viz., ethyl 4-[(4-chlorophenyl)amino]-6-methyl-2-oxocyclohex-3-en-1-oate.
2. Description of the Related Art
Coughs, particularly chronic coughs, are a very common clinical problem with a high prevalence rate. Unfortunately, current over-the-counter drugs provide very little therapeutic benefit and often have serious side effects. Due to a lack of treatment alternatives, these drugs still remain among the most widely used drugs. There is evidence to show that some types of coughs, such as the nonproductive chronic cough associated with smoking, seems to improve following administration of β2 agonists, which suggests that this type of cough is bronchodilator sensitive. Additionally, patients with a nonproductive cough associated with airflow obstruction seem to derive improvement in their cough following β2 agonist treatment.
Treatment with a combination of the antitussive agent dextromethorphan and salbutamol (salbutamol is the International Nonproprietary Name; albuterol is the U.S. Adopted Name) has been reported to be more effective in reducing citric acid-induced cough than dextromethorphan alone. Also, dextromethorphan and salbutamol were more effective in treating acute transient cough than dextromethorphan alone. In order to provide both antitussive and bronchodilator treatment, both drugs must be used. It would be desirable to provide a single cough suppressant providing antitussive and bronchodilator properties for treatment of a nonproductive cough.
Further, dextromethorphan is addictive and has severe side effects, including nausea, drowsiness, dizziness, hallucinations, vomiting, blurred vision, sweating, dilated pupils, hypertension and shallow respiration. Dextromethorphan is commonly abused as a recreational drug. Salbutamol also has severe side effects, including tremor, nervousness, headache, muscle cramps, dry mouth and palpitation. It would be desirable to provide an alternative for both drugs.
Although a comprehensive program of medical treatment would involve efforts to identify the underlying cause for nonproductive coughing and tailoring a treatment program towards the underlying cause, nevertheless, in many cases nonproductive coughing is a symptom that causes the patient discomfort, distress (either physical or social from an inability to suppress coughing when desired), an inability to sleep comfortably with resulting fatigue, and the like, so that often the patient desires at least temporary relief from the symptom, regardless of the underlying cause. Of course, it is generally not desirable to suppress a productive cough, but an antitussive, or an antitussive in combination with a bronchodilator when the cough is accompanied by bronchoconstriction, is useful for temporary symptomatic treatment or relief from a nonproductive cough. Thus, antitussive and bronchodilator use for an enaminone ester solving the aforementioned problems is desired.